Heterogeneous Distribution of Weedy Paspalum Species and Edaphic Variables in Turfgrass

Abstract

Dallisgrass (Paspalum dilatatum Poir.) and bahiagrass (Paspalum notatum Fluegge) are two of the most troublesome weed species in managed turfgrass. These rhizomatous, perennial grass species affect appearance, texture, and playability of turf in home lawns, golf courses, and athletic fields. The severity and prevalence of these problem species as well as the difficulty of achieving control with herbicide management alone invite the examination of their realized niches for clues to improved management tactics. The distribution of these species was evaluated in both fairways and roughs of three holes on each of two golf courses in North Carolina. Golf courses were selected based on the presence of both weed species. Individual plants were mapped using a high-precision global positioning system unit. This unit was also used to delineate between the rough and fairway height of cut as well as obtain elevation characteristics of each hole. Soil moisture and soil compaction estimates were obtained by sampling on a 9-m grid. Environmental characteristics used for χ2 analysis consisted of mowing height, soil compaction, soil moisture, and elevation. Data were subjected to χ2 analysis to determine if the existing distribution of Paspalum spp. differed from an expected random distribution across all environmental factors. Bahiagrass growth and distribution was more affected by mowing height than dallisgrass. Bahiagrass was predominantly distributed in the rough, whereas dallisgrass occurred at both mowing heights. Similar responses were observed for both species with regard to soil compaction. Higher plant density for both species was observed in moderately compacted soil (40 to 60 N·m−2). Bahiagrass distribution was unaffected by soil moisture. Dallisgrass density was lower in areas with low volumetric soil water content (less than 27%). Although different from an expected uniform distribution on all six holes, the elevation with the highest Paspalum spp. density varied across holes. Results suggest that it may be possible to disadvantage Paspalum spp. in competitive interactions with desirable species through the alteration of landscape attributes. Substrate selection during construction, aeration, and mowing height may help create a landscape that discourages Paspalum spp. infestation.